In various instances it is desired to cool, and maintain cool, the interior of a mobile normally closed and insulated storage area. Such storage areas may comprise the load bodies of trucks utilized to transport perishables.
Although some trucks include mechanical refrigeration units for refrigerating the interior of the load bodies thereof, such mechanically refrigerated load bodies are expensive and frequently experience mechanical failures. In addition, a mechanically refrigerated load body equipped truck is not always available when an urgent need for transporting perishable items arises.
Therefore, a need exists for structure whereby the interior of a normally closed load body may be cooled and maintained in a cooled state.
Although various forms of non-mechanical refrigeration units have been heretofore designed such as that disclosed in my prior U.S. Pat. No. 3,744,271, such non-mechanical refrigeration units, in most cases, utilize liquid nitrogen and the vaporization of the liquid nitrogen to provide the necessary cooling action. However, the cost of liquid nitrogen has recently increased to the point rendering its utilization on a large scale cost prohibitive. Accordingly, a need exists for an improved form of cooling unit, of the cold holdover type, and which may be "charged" at a lower cost.